In recent years, semiconductor devices, such as flash memories, have tended to become highly integrated. Thus, a pattern size is markedly being downscaled. When a pattern is formed, a predetermined processing process, such as an oxidation process or a nitridation process, may be performed on a substrate as one of manufacturing processes.
As a method of forming the pattern, a groove is formed between circuits, and a liner film or interconnection is formed within the groove. The groove is configured to have a high aspect ratio with the recent miniaturization.
When the liner film is formed, it is necessary to form a film having good step coverage, which has no deviation in film thickness, on an upper side surface, a middle side surface, a lower side surface and bottom portion of the groove. By forming the film having the good step coverage, characteristics of a semiconductor device may be uniformized, so that deviations in the characteristics of the semiconductor device may be inhibited.
To process the groove having the high aspect ratio, a process of processing the groove by heating gases or using gases in a plasma state has been attempted, but it is difficult to form a film having good step coverage.
As methods of forming the film, there are a chemical vapor deposition (CVD) method and an atomic layer deposition (ALD) method of forming films by causing a reaction between at least two types of process gases.
Here, since it is necessary to uniformize characteristics of a semiconductor substrate, gases need to be uniformly supplied to an in-plane surface of the substrate when forming a thin film. To realize the uniform supplying of the gases, a single-wafer-type apparatus capable of uniformly supplying gases to a process surface of the substrate is being developed. In the single-wafer-type apparatus, for example, a shower head including a buffer chamber is installed over the substrate to supply gases more uniformly.
Conventionally, a technique of improving in-plane uniformity of a film forming process by uniformizing the amount of process gas consumed due to the film forming process and the amount of process gas supplied to a process space through a head unit per unit area using a structure in which a support body of a processed body has the same diameter as a shower head unit, a technique of forming a gas introduction unit in such a shape as to protrude into a process chamber and installing a plurality of gas introduction holes to be opened in different directions such that gases do not diffuse due to a distance between a shower head and a lower electrode on which a substrate is placed when a poly silicon (poly-Si) layer disposed on the substrate is etched using the shower head, and a technique of installing an on-axis spray supply hole of supplying a process gas to a first region by which the process gas is supplied in an axial direction vertical to a surface of a substrate and an off-axis spray supply hole of supplying a process gas to a second region by which the process gas is supplied in an inclined direction, have been developed.
When a desired film is formed by at least two types of process gases using a single-wafer-type apparatus, the film is formed by causing a reaction between the at least two types of process gases above a substrate or on a surface of the substrate. However, in a conventional apparatus configured to supply gases via a buffer chamber, it is inferred that the gases react in the buffer chamber to generate byproducts in the buffer chamber. There are some cases in which the generated byproducts adversely affect characteristics of a substrate.
In addition, when a gas supply process is performed using a shower head in a single-wafer-type apparatus, since a distance by which a reactive gas uniformly flowing out through the shower head flows on a surface of a substrate varies according to an outflow spot, in-plane uniformity deteriorates.